Channel State Information Feedback Method and Apparatus

ABSTRACT

A channel state information feedback method and an apparatus to flexibly feed back channel state information, to implement balance between feedback overheads and feedback precision of the channel state information. The method includes: sending a media access control (MAC) frame, where the MAC frame includes a processing mode bitmap, every n bits in the processing mode bitmap correspond to one feedback unit, and a value of the n bits is used to indicate a processing mode of channel state information of the corresponding feedback unit; and receiving a beamforming report, where the beamforming report includes one or more feedback fields, each feedback field corresponds to one feedback unit, the feedback field includes channel state information of the corresponding feedback unit, and the channel state information included in the feedback field is processed in a processing mode indicated by the processing mode bitmap.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2019/116318, filed on Nov. 7, 2019, which claims priority toChinese Patent Application No. 201811321478.9, filed on Nov. 7, 2018.The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the field of communications technologies,and in particular, to a channel state information feedback method and anapparatus.

BACKGROUND

In a wireless communications system such as a wireless local areanetwork (WLAN), a multiple-input multiple-output (MIMO) technology is awidely used technology. When the MIMO technology is used, a beamformerneeds to obtain channel state information from a beamformee, such thatthe beamformer implements functions such as beamforming, rate control,and resource allocation based on the channel state information.

An 802.11 standard is a universal WLAN standard. Currently, theInstitute of Electrical and Electronics Engineers (IEEE) is discussing anext generation 802.11 standard after 802.11ax. Compared with theprevious 802.11 standard, the next generation 802.11 standard supportsdata transmission with an extremely high throughput (EHT), that is, thenext generation 802.11 standard supports a higher bandwidth (forexample, 320 megahertz (MHz)) and more streams (for example, 16 spatialstreams). In this way, the beamformee needs to feed back more pieces ofchannel state information to the beamformer, resulting in excessivelyhigh feedback overheads. Therefore, for the next generation 802.11standard, how to feed back channel state information and implementbalance between feedback overheads and feedback precision of the channelstate information is an urgent problem to be resolved.

SUMMARY

This application provides a channel state information feedback methodand an apparatus, to flexibly feed back channel state information, so asto implement balance between feedback overheads and feedback precisionof the channel state information.

To achieve the foregoing objective, this application provides thefollowing technical solutions.

According to a first aspect, a channel state information feedback methodis provided, and includes the following steps: A beamformer sends amedia access control (MAC) frame, where the MAC frame includes aprocessing mode bitmap, every n bits in the processing mode bitmapcorrespond to one feedback unit, a value of the n bits is used toindicate a processing mode of channel state information of thecorresponding feedback unit, and n is a positive integer; and thebeamformer receives a beamforming report sent by a beamformee, where thebeamforming report includes one or more feedback fields, each feedbackfield corresponds to one feedback unit, the feedback field includeschannel state information of the corresponding feedback unit, and thechannel state information of the corresponding feedback unit isprocessed in a processing mode indicated by the processing mode bitmap.

Based on the foregoing technical solution, every n bits in theprocessing mode bitmap correspond to one feedback unit, and the value ofthe n bits is used to indicate the processing mode of the channel stateinformation of the corresponding feedback unit. It may be understoodthat different processing modes correspond to different feedbackoverheads and different feedback precision. Therefore, for channel stateinformation of some feedback units (for example, relatively importantchannels), the beamformer may indicate, using the processing modebitmap, the beamformee to use a processing mode with relatively highfeedback precision, to ensure feedback precision. For channel stateinformation of some other feedback units (for example, unimportantchannels), the beamformer may indicate, using the processing modebitmap, the beamformee to use a processing mode with relatively lowfeedback overheads, to reduce feedback overheads. In this way, thebeamformer may configure a proper processing mode based on arequirement, and indicate the beamformee to process channel stateinformation of different feedback units in different processing modes,to implement balance between feedback overheads and feedback precisionof the channel state information when the channel state information isfed back.

In a possible design, the feedback unit is a segment, a resource unit,or a channel.

In a possible design, the MAC frame is a null data packet announcement(NDPA) frame or a beamforming report poll trigger frame.

According to a second aspect, a channel state information feedbackmethod is provided, and includes the following steps: A beamformeereceives a MAC frame sent by a beamformer, where the MAC frame includesa processing mode bitmap, every n bits in the processing mode bitmapcorrespond to one feedback unit, a value of the n bits is used toindicate a processing mode of channel state information of thecorresponding feedback unit, and n is a positive integer; and thebeamformee sends a beamforming report to the beamformer, where thebeamforming report includes one or more feedback fields, each feedbackfield corresponds to one feedback unit, the feedback field includeschannel state information of the corresponding feedback unit, and thechannel state information of the corresponding feedback unit isprocessed in a processing mode indicated by the processing mode bitmap.

Based on the foregoing technical solution, every n bits in theprocessing mode bitmap correspond to one feedback unit, and the value ofthe n bits is used to indicate the processing mode of the channel stateinformation of the corresponding feedback unit. It may be understoodthat different processing modes correspond to different feedbackoverheads and different feedback precision. Therefore, for channel stateinformation of some feedback units (for example, relatively importantchannels), the beamformer may indicate, using the processing modebitmap, the beamformee to use a processing mode with relatively highfeedback precision, to ensure feedback precision. For channel stateinformation of some other feedback units (for example, unimportantchannels), the beamformer may indicate, using the processing modebitmap, the beamformee to use a processing mode with relatively lowfeedback overheads, to reduce feedback overheads. In this way, thebeamformer may configure a proper processing mode based on arequirement, and indicate the beamformee to process channel stateinformation of different feedback units in different processing modes,to implement balance between feedback overheads and feedback precisionof the channel state information when the channel state information isfed back.

In a possible design, the feedback unit is a segment, a resource unit,or a channel.

In a possible design, the MAC frame is an NDPA frame or a beamformingreport poll trigger frame.

According to a third aspect, a channel state information feedback methodis provided, and includes the following steps: A beamformer sends a MACframe, where the MAC frame includes at least two pieces of userinformation corresponding to a target beamformee, and at least one typeof configuration parameters in configuration parameters included in theat least two pieces of user information have different values; and thebeamformer receives a beamforming report sent by the target beamformee,where the beamforming report includes channel state informationrespectively corresponding to the at least two pieces of userinformation.

Based on the foregoing technical solution, the MAC frame may include theat least two pieces of user information corresponding to the targetbeamformee, and the at least one type of configuration parameters in theconfiguration parameters included in the at least two pieces of userinformation have different values. To be more specific, the beamformermay indicate, using a plurality of pieces of user informationcorresponding to the target beamformee in the MAC frame, the targetbeamformee to feed back a plurality of pieces of channel stateinformation, where the plurality of pieces of channel state informationmay be processed in different processing modes, and/or the plurality ofpieces of channel state information are channel state information ofresource units at different parts. In this way, the channel stateinformation is flexibly fed back.

In a possible design, the user information includes one or more of thefollowing configuration parameters: a resource unit start index, aresource unit end index, processing mode indication information, anumber of grouping, or codebook information.

In a possible design, the MAC frame is an NDPA frame or a beamformingreport poll trigger frame.

According to a fourth aspect, a channel state information feedbackmethod is provided, and includes the following steps: A targetbeamformee receives a MAC frame sent by a beamformer, where the MACframe includes at least two pieces of user information corresponding tothe target beamformee, and at least one type of configuration parametersin configuration parameters included in the at least two pieces of userinformation have different values; and the target beamformee sends abeamforming report to the beamformer, where the beamforming reportincludes channel state information respectively corresponding to the atleast two pieces of user information.

Based on the foregoing technical solution, the MAC frame may include theat least two pieces of user information corresponding to the targetbeamformee, and the at least one type of configuration parameters in theconfiguration parameters included in the at least two pieces of userinformation have different values. To be more specific, the beamformermay indicate, using a plurality of pieces of user informationcorresponding to the target beamformee in the MAC frame, the targetbeamformee to feed back a plurality of pieces of channel stateinformation, where the plurality of pieces of channel state informationmay be processed in different processing modes, and/or the plurality ofpieces of channel state information are channel state information ofresource units at different parts. In this way, the channel stateinformation is flexibly fed back.

In a possible design, the user information includes one or more of thefollowing configuration parameters: a resource unit start index, aresource unit end index, processing mode indication information, anumber of grouping, or codebook information.

In a possible design, the MAC frame is an NDPA frame or a beamformingreport poll trigger frame.

According to a fifth aspect, a communications apparatus is provided. Thecommunications apparatus is configured to perform the method accordingto the first aspect or any possible implementation of the first aspect.For example, the communications apparatus includes a unit configured toperform the method according to the first aspect or any possibleimplementation of the first aspect.

According to a sixth aspect, a communications apparatus is provided. Thecommunications apparatus is configured to perform the method accordingto the second aspect or any possible implementation of the secondaspect. For example, the communications apparatus includes a unitconfigured to perform the method according to the second aspect or anypossible implementation of the second aspect.

According to a seventh aspect, a communications apparatus is provided.The communications apparatus is configured to perform the methodaccording to the third aspect or any possible implementation of thethird aspect. For example, the communications apparatus includes a unitconfigured to perform the method according to the third aspect or anypossible implementation of the third aspect.

According to an eighth aspect, a communications apparatus is provided.The communications apparatus is configured to perform the methodaccording to the fourth aspect or any possible implementation of thefourth aspect. For example, the communications apparatus includes a unitconfigured to perform the method according to the fourth aspect or anypossible implementation of the fourth aspect.

According to a ninth aspect, a communications device is provided. Thecommunications device includes a processor and a transceiver, andoptionally, further includes a memory. The processor communicates withthe transceiver and the memory through an internal connection. Theprocessor is configured to perform the method according to the firstaspect or any possible implementation of the first aspect. Thetransceiver is controlled by the processor, and is configured to performthe method according to the first aspect or any possible implementationof the first aspect. The memory is configured to store instructions. Theinstructions are invoked by the processor to perform the methodaccording to the first aspect or any possible implementation of thefirst aspect.

According to a tenth aspect, a communications device is provided. Thecommunications device includes a processor and a transceiver, andoptionally, further includes a memory. The processor communicates withthe transceiver and the memory through an internal connection. Theprocessor is configured to perform the method according to the secondaspect or any possible implementation of the second aspect. Thetransceiver is controlled by the processor, and is configured to performthe method according to the second aspect or any possible implementationof the second aspect. The memory is configured to store instructions.The instructions are invoked by the processor to perform the methodaccording to the second aspect or any possible implementation of thesecond aspect.

According to an eleventh aspect, a communications device is provided.The communications device includes a processor and a transceiver, andoptionally, further includes a memory. The processor communicates withthe transceiver and the memory through an internal connection. Theprocessor is configured to perform the method according to the thirdaspect or any possible implementation of the third aspect. Thetransceiver is controlled by the processor, and is configured to performthe method according to the third aspect or any possible implementationof the third aspect. The memory is configured to store instructions. Theinstructions are invoked by the processor to perform the methodaccording to the third aspect or any possible implementation of thethird aspect.

According to a twelfth aspect, a communications device is provided. Thecommunications device includes a processor and a transceiver, andoptionally, further includes a memory. The processor communicates withthe transceiver and the memory through an internal connection. Theprocessor is configured to perform the method according to the fourthaspect or any possible implementation of the fourth aspect. Thetransceiver is controlled by the processor, and is configured to performthe method according to the fourth aspect or any possible implementationof the fourth aspect. The memory is configured to store instructions.The instructions are invoked by the processor to perform the methodaccording to the fourth aspect or any possible implementation of thefourth aspect.

According to a thirteenth aspect, a computer-readable storage medium isprovided. The computer-readable storage medium is configured to store acomputer program. The computer program includes instructions used toperform the method according to the first aspect or any possibleimplementation of the first aspect.

According to a fourteenth aspect, a computer-readable storage medium isprovided. The computer-readable storage medium is configured to store acomputer program. The computer program includes instructions used toperform the method according to the second aspect or any possibleimplementation of the second aspect.

According to a fifteenth aspect, a computer-readable storage medium isprovided. The computer-readable storage medium is configured to store acomputer program. The computer program includes instructions used toperform the method according to the third aspect or any possibleimplementation of the third aspect.

According to a sixteenth aspect, a computer-readable storage medium isprovided. The computer-readable storage medium is configured to store acomputer program. The computer program includes instructions used toperform the method according to the fourth aspect or any possibleimplementation of the fourth aspect.

According to a seventeenth aspect, a computer program is provided. Thecomputer program includes instructions used to perform the methodaccording to the first aspect or any possible implementation of thefirst aspect.

According to an eighteenth aspect, a computer program is provided. Thecomputer program includes instructions used to perform the methodaccording to the second aspect or any possible implementation of thesecond aspect.

According to a nineteenth aspect, a computer program is provided. Thecomputer program includes instructions used to perform the methodaccording to the third aspect or any possible implementation of thethird aspect.

According to a twentieth aspect, a computer program is provided. Thecomputer program includes instructions used to perform the methodaccording to the fourth aspect or any possible implementation of thefourth aspect.

According to a twenty-first aspect, a chip is provided. The chipincludes a processing circuit and a transceiver pin, and optionally,further includes a memory. The processing circuit communicates with thetransceiver pin and the memory through an internal connection. Theprocessing circuit is configured to perform the method according to thefirst aspect or any possible implementation of the first aspect. Thetransceiver pin is controlled by the processing circuit, and isconfigured to perform the method according to the first aspect or anypossible implementation of the first aspect. The memory is configured tostore instructions. The instructions are invoked by the processingcircuit to perform the method according to the first aspect or anypossible implementation of the first aspect.

According to a twenty-second aspect, a chip is provided. The chipincludes a processing circuit and a transceiver pin, and optionally,further includes a memory. The processing circuit communicates with thetransceiver pin and the memory through an internal connection. Theprocessing circuit is configured to perform the method according to thesecond aspect or any possible implementation of the second aspect. Thetransceiver pin is controlled by the processing circuit, and isconfigured to perform the method according to the second aspect or anypossible implementation of the second aspect. The memory is configuredto store instructions. The instructions are invoked by the processingcircuit to perform the method according to the second aspect or anypossible implementation of the second aspect.

According to a twenty-third aspect, a chip is provided. The chipincludes a processing circuit and a transceiver pin, and optionally,further includes a memory. The processing circuit communicates with thetransceiver pin and the memory through an internal connection. Theprocessing circuit is configured to perform the method according to thethird aspect or any possible implementation of the third aspect. Thetransceiver pin is controlled by the processing circuit, and isconfigured to perform the method according to the third aspect or anypossible implementation of the third aspect. The memory is configured tostore instructions. The instructions are invoked by the processingcircuit to perform the method according to the third aspect or anypossible implementation of the third aspect.

According to a twenty-fourth aspect, a chip is provided. The chipincludes a processing circuit and a transceiver pin, and optionally,further includes a memory. The processing circuit communicates with thetransceiver pin and the memory through an internal connection. Theprocessing circuit is configured to perform the method according to thefourth aspect or any possible implementation of the fourth aspect. Thetransceiver pin is controlled by the processing circuit, and isconfigured to perform the method according to the fourth aspect or anypossible implementation of the fourth aspect. The memory is configuredto store instructions. The instructions are invoked by the processingcircuit to perform the method according to the fourth aspect or anypossible implementation of the fourth aspect.

For technical effects brought by any implementation in the fifth aspectto the twenty-fourth aspect, refer to the beneficial effects in thecorresponding method provided in the foregoing description. Details arenot described herein again.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a single-user feedback procedure ofchannel state information in an 802.11ax standard;

FIG. 2 is a schematic diagram of a multi-user feedback procedure ofchannel state information in an 802.11ax standard;

FIG. 3 is a flowchart 1 of a channel state information feedback methodaccording to an embodiment of this application;

FIG. 4 is a schematic structural diagram 1 of a MIMO control fieldaccording to an embodiment of this application;

FIG. 5 is a schematic structural diagram 2 of a MIMO control fieldaccording to an embodiment of this application;

FIG. 6 is a schematic structural diagram 3 of a MIMO control fieldaccording to an embodiment of this application;

FIG. 7 is a flowchart 2 of a channel state information feedback methodaccording to an embodiment of this application;

FIG. 8 is a schematic structural diagram 1 of an NDPA frame according toan embodiment of this application;

FIG. 9 is a schematic structural diagram 2 of an NDPA frame according toan embodiment of this application;

FIG. 10 is a flowchart 3 of a channel state information feedback methodaccording to an embodiment of this application;

FIG. 11 is a schematic structural diagram 1 of a BRP trigger frameaccording to an embodiment of this application;

FIG. 12 is a schematic structural diagram 2 of a BRP trigger frameaccording to an embodiment of this application;

FIG. 13 is a flowchart 4 of a channel state information feedback methodaccording to an embodiment of this application;

FIG. 14 is a schematic structural diagram 4 of a MIMO control fieldaccording to an embodiment of this application;

FIG. 15 is a flowchart 5 of a channel state information feedback methodaccording to an embodiment of this application;

FIG. 16 is a schematic structural diagram 3 of an NDPA frame accordingto an embodiment of this application;

FIG. 17 is a schematic structural diagram 4 of an NDPA frame accordingto an embodiment of this application;

FIG. 18 is a flowchart 6 of a channel state information feedback methodaccording to an embodiment of this application;

FIG. 19 is a schematic structural diagram 3 of a BRP trigger frameaccording to an embodiment of this application;

FIG. 20 is a schematic structural diagram 4 of a BRP trigger frameaccording to an embodiment of this application;

FIG. 21 is a schematic structural diagram 5 of a BRP trigger frameaccording to an embodiment of this application;

FIG. 22 is a schematic structural diagram of a communications apparatusaccording to an embodiment of this application; and

FIG. 23 is a schematic structural diagram of a communications deviceaccording to an embodiment of this application.

DESCRIPTION OF EMBODIMENTS

The following first briefly describes some concepts.

(1) Feedback procedure of channel state information in an 802.11axstandard

Currently, feedback procedures of channel state information in the802.11ax standard are classified into a single-user feedback procedureand a multi-user feedback procedure. The following uses an example inwhich a beamformer is an access point (AP) and a beamformee is a station(STA) for description.

As shown in FIG. 1, in the single-user feedback procedure, an AP sendsan NDPA frame, to indicate a target STA (for example, an STA 1 inFIG. 1) to prepare for channel estimation. Then, the AP sends a nulldata packet (null data packet, NDP), such that the target STA performschannel estimation based on a long training sequence in the NDP, todetermine channel state information. The target STA sends a beamformingreport to the AP, and the beamforming report includes the channel stateinformation.

For example, both an interframe space between the NDPA frame and the NDPand an interframe space between the NDP and the beamforming report areshort interframe spaces (SIFS).

As shown in FIG. 2, in the multi-user feedback procedure, an AP sends anNDPA frame, to indicate a plurality of target STAs (such as a STA 1, aSTA 2, and a STA 3 in FIG. 2) to prepare for channel estimation. Then,the AP sends an NDP, such that the plurality of target STAs performchannel estimation. The AP sends a beamforming report poll (BRP) triggerframe to trigger the plurality of target STAs to feed back channel stateinformation. The plurality of target STAs each send a beamforming reportto the AP.

It should be noted that the NDPA frame, the BRP trigger frame, and thebeamforming report are all MAC frames.

(2) Resource Unit (RU)

The resource unit is a frequency domain resource, and the resource unitincludes one or more subcarriers. Currently, the following types of RUsare defined in a WLAN system: a 26-subcarrier RU (to be more specific,one RU includes 26 subcarriers), a 52-subcarrier RU (to be morespecific, one RU includes 52 subcarriers), a 106-subcarrier RU (to bemore specific, one RU includes 106 subcarriers), a 242-subcarrier RU (tobe more specific, one RU includes 242 subcarriers), a 484-subcarrier RU(to be more specific, one RU includes 484 subcarriers), a 996-subcarrierRU (to be more specific, one RU includes 996 subcarriers), and the like.

Currently, channel bandwidths (CBWs) supported by the 802.11ax standardare: 20 MHz, 40 MHz, 80 MHz, 80+80 MHz (to be more specific, twochannels with a bandwidth of 80 MHz are supported, and the two channelsare non-contiguous and non-overlapping), and 160 MHz. Table 1 shows atotal quantity of RUs in each channel bandwidth.

TABLE 1 CBW 160 and RU type CBW 20 CBW 40 CBW 80 CBW 80 + 8026-subcarrier RU 9 18 37 74 52-subcarrier RU 4 8 16 32 106-subcarrier RU2 4 8 16 242-subcarrier RU 1 2 4 8 484-subcarrier RU Not applicable(N/A) 1 2 4 996-subcarrier RU N/A N/A 1 2 2 × 996-subcarrier RU N/A N/AN/A 1

(3) Segment

The beamforming report may be divided into eight segments. In this case,the channel state information included in the beamforming report is alsodivided into eight parts, and each segment carries one part of thechannel state information.

The following describes the technical solutions in the embodiments ofthis application with reference to the accompanying drawings in theembodiments of this application. In the descriptions of thisapplication, “/” means “or” unless otherwise specified. For example, A/Bmay represent A or B. The term “and/or” in this specification describesonly an association relationship for describing associated objects andrepresents that three relationships may exist. For example, A and/or Bmay represent the following three cases: Only A exists, both A and Bexist, and only B exists. In addition, “at least one” means one or more,and “a plurality of” means two or more.

Words such as “first” and “second” do not limit a quantity and anexecution sequence, and the words such as “first” and “second” do notindicate a definite difference.

The technical solutions of this application are applied to a WLAN. Astandard used for the WLAN may be an IEEE 802.11 standard such as an802.11ac standard, an 802.11ax standard, or a next generation 802.11standard. The technical solutions of this application are applicable toscenarios such as communication between an AP and a STA, communicationbetween APs, and communication between STAs. In the embodiments of thisapplication, the AP may be used as a beamformer, or may be used as abeamformee. The STA may be used as a beamformer, or may be used as abeamformee. The AP may be a wireless router, a wireless transceiver, awireless switch, or the like. The STA has different names such as asubscriber unit, an access terminal, a mobile station, a mobile console,a mobile device, a terminal, and user equipment. During actualapplication, the STA may be a cellular phone, a smartphone, a wirelesslocal loop (WLL), another handheld device that has a wireless local areanetwork communication function, or a computer device.

FIG. 3 shows a channel state information feedback method according to anembodiment of this application. The method includes the following steps.

S101: A beamformer generates and sends a MAC frame, where the MAC frameincludes a processing mode bitmap.

The MAC frame is an NDPA frame or a BRP trigger frame.

In a possible implementation, the beamformer sends the MAC frame in abroadcast manner.

It should be noted that the processing mode bitmap is used to indicateprocessing modes of channel state information of a plurality of feedbackunits, and the processing modes of the channel state information of theplurality of feedback units may be the same or different.

In this embodiment of this application, a plurality of differentprocessing modes are pre-specified between the beamformer and abeamformee. Optionally, feedback overheads corresponding to thedifferent processing modes are different. For example, numbers ofgrouping used in the different processing modes are different, and/orquantization levels used in the different processing modes aredifferent. It should be noted that the number of grouping is used toindicate a quantity of subcarriers that are grouped into one group. Itshould be noted that, for a group of subcarriers, the beamformee needsto feed back channel state information of only one subcarrier in thegroup of subcarriers, to reduce feedback overheads.

For example, the foregoing processing modes include a first processingmode and a second processing mode. Feedback overheads corresponding tothe first processing mode are higher than feedback overheadscorresponding to the second processing mode in one of the followingcases: (1) A number of grouping used in the first processing mode isless than a number of grouping used in the second processing mode; (2) anumber of grouping used in the first processing mode is greater than thenumber of grouping used in the second processing mode; and (3) the firstprocessing mode is a non-differential processing mode, and the secondprocessing mode is a differential processing mode. The differentialprocessing mode is to perform difference calculation on current channelstate information and previously buffered channel state information, todetermine a channel state information difference. In this way, thebeamformee feeds back the channel state information difference to thebeamformer. The beamformer determines the current channel stateinformation based on the channel state information difference and thepreviously buffered channel state information. Compared with a channelstate information absolute value, the channel state informationdifference has a smaller variation range. Therefore, fewer quantizationbits may be used to represent the channel state information difference,to reduce feedback overheads.

For example, the channel state information includes a feedback matrix(such as a V matrix) and a signal-to-noise ratio (SNR). Optionally, theforegoing processing mode may be a processing mode for one parameter(for example, the feedback matrix or the signal-to-noise ratio) in thechannel state information, or may be a processing mode for a pluralityof parameters (for example, the feedback matrix and the signal-to-noiseratio) in the channel state information.

In this embodiment of this application, one feedback unit may include atleast one segment, at least one RU, or at least one channel. Forexample, the feedback unit is a 26-subcarrier RU, a 52-subcarrier RU, ora 242-subcarrier RU. For another example, the feedback unit is a channelwith a bandwidth of 20 MHz, a channel with a bandwidth of 40 MHz, or achannel with a bandwidth of 80 MHz.

For example, in the processing mode bitmap, every n bits correspond toone feedback unit, a value of the n bits is used to indicate aprocessing mode of channel state information of the correspondingfeedback unit, and n is a positive integer. For example, in theprocessing mode bitmap, the first to the n^(th) bits correspond to afirst feedback unit, the (n+1)^(th) to the (2n)^(th) bits correspond toa second feedback unit, and by analogy, the (Ln+1)^(th) to the(Ln+n)^(th) bits correspond to an L^(th) feedback unit. L is an integergreater than or equal to 0.

In this embodiment of this application, a specific value of n ispreconfigured, is defined in a standard, or is indicated by thebeamformer. For example, the MAC frame further includes a valueindication field, and the value indication field is used to indicate thevalue of n.

Optionally, there is a correspondence between a value of n and aquantity of processing modes. For example, 2^(n−1)≤M≤2^(n), or M≤2^(n),where M is the quantity of processing modes. For example, if theprocessing modes include only the first processing mode and the secondprocessing mode, the value of n is 1. In other words, each bit in theprocessing mode bitmap corresponds to one feedback unit. For anotherexample, if the processing modes include the first processing mode, thesecond processing mode, and a third processing mode, the value of n is2. In other words, every two bits in the processing mode bitmapcorrespond to one feedback unit.

Optionally, a type of the feedback unit corresponding to the n bits inthe processing mode bitmap is preconfigured or defined in the standard.To be more specific, whether the n bits in the processing mode bitmapcorrespond to the 26-subcarrier RU or the 52-subcarrier RU, orcorrespond to the channel with the bandwidth of 40 MHz is preconfiguredor defined in the standard.

Optionally, the type of the feedback unit corresponding to the n bits inthe processing mode bitmap is indicated by the beamformer.

In an implementation, the beamformer indicates, in an implicit manner,the type of the feedback unit corresponding to the n bits in theprocessing mode bitmap. For example, a total quantity of bits includedin the processing mode bitmap is used to indicate the type of thefeedback unit. For example, if each bit in the processing mode bitmapcorresponds to one feedback unit, and the total quantity of bitsincluded in the processing mode bitmap is 8, a type of a feedback unitcorresponding to one bit in the processing mode bitmap is a segment,that is, each bit in the processing mode bitmap corresponds to onesegment. For another example, it is assumed that a bandwidth of ato-be-detected channel is 320 MHz. If each bit in the processing modebitmap corresponds to one feedback unit, and the total quantity of bitsincluded in the processing mode bitmap is 8, a type of a feedback unitcorresponding to one bit in the processing mode bitmap is a channel witha bandwidth of 40 MHz. For another example, it is assumed that abandwidth of a to-be-detected channel is 320 MHz. If each bit in theprocessing mode bitmap corresponds to one feedback unit, and the totalquantity of bits included in the processing mode bitmap is 16, a type ofa feedback unit corresponding to one bit in the processing mode bitmapis a channel with a bandwidth of 20 MHz. For another example,descriptions are provided with reference to Table 1. It is assumed thata bandwidth of a to-be-detected channel is 160 MHz. If each bit in theprocessing mode bitmap corresponds to one feedback unit, and the totalquantity of bits included in the processing mode bitmap is 16, a type ofa feedback unit corresponding to one bit in the processing mode bitmapis a 106-subcarrier RU. For another example, descriptions are providedwith reference to Table 1. It is assumed that a bandwidth of ato-be-detected channel is 160 MHz. If each bit in the processing modebitmap corresponds to one feedback unit, and the total quantity of bitsincluded in the processing mode bitmap is 74, a type of a feedback unitcorresponding to one bit in the processing mode bitmap is a26-subcarrier RU.

It should be noted that the MAC frame may include or not include partialbandwidth information, where the partial bandwidth information is usedto indicate a partial channel bandwidth. For example, the partialbandwidth information includes a resource unit start index and aresource unit end index. The resource unit start index and the resourceunit end index are used to indicate a segment of contiguous resourceunits. For example, if the resource unit start index is 0, and theresource unit end index is 10, the resource unit start index and theresource unit end index are used to indicate the first to the eleventh26-subcarrier RUs. It should be noted that an index of a resource unitis defined in the standard. If the MAC frame does not include thepartial bandwidth information, the MAC frame is used to request thebeamformee to feed back channel state information in an entire channelbandwidth. If the MAC frame includes the partial bandwidth information,the MAC frame is used to request the beamformee to feed back channelstate information in the partial channel bandwidth.

Optionally, the type of the feedback unit corresponding to every n bitsin the processing mode bitmap is related to whether the MAC frameincludes the partial bandwidth information. For example, the MAC framedoes not include the partial bandwidth information, and the entirechannel bandwidth is 320 MHz. In this case, if each bit in theprocessing mode bitmap corresponds to one feedback unit, and the totalquantity of bits included in the processing mode bitmap is 16, a type ofa feedback unit corresponding to one bit in the processing mode bitmapis a channel with a bandwidth of 20 MHz. For another example, the MACframe includes the partial bandwidth information, the resource unitstart index in the partial bandwidth information is 0, and the resourceunit end index in the partial bandwidth information is 15. In this case,if each bit in the processing mode bitmap corresponds to one feedbackunit, and the total quantity of bits included in the processing modebitmap is 16, a type of a feedback unit corresponding to one bit in theprocessing mode bitmap is a 26-subcarrier RU.

Optionally, if the MAC frame includes the partial bandwidth information,and the feedback unit is an RU, which RU corresponds to every n bits inthe processing mode bitmap may be determined with reference to thepartial bandwidth information. For example, the MAC frame includes thepartial bandwidth information, the resource unit start index in thepartial bandwidth information is 7, and the resource unit end index inthe partial bandwidth information is 14. In this case, if the totalquantity of bits included in the processing mode bitmap is 8, in theprocessing mode bitmap, the first bit corresponds to the eighth26-subcarrier RU, the second bit corresponds to the ninth 26-subcarrierRU, and by analogy, the eighth bit corresponds to the fifteenth26-subcarrier RU.

In another implementation, the beamformer indicates, in an explicitmanner, the type of the feedback unit corresponding to the n bits in theprocessing mode bitmap. For example, the MAC frame also includes afeedback unit indication field, and the feedback unit indication fieldis used to indicate the type of the feedback unit corresponding to the nbits in the processing mode bitmap.

S102: The beamformer receives a beamforming report sent by thebeamformee.

The beamforming report includes one or more feedback fields, eachfeedback field corresponds to one feedback unit, the feedback fieldincludes channel state information of the corresponding feedback unit,and the channel state information included in the feedback field isprocessed in a processing mode indicated by the processing mode bitmap.

In an implementation, the beamforming report may further include one ormore MIMO control fields, each MIMO control field corresponds to onefeedback field, and the MIMO control field is used to indicate aconfiguration parameter used for channel state information included inthe corresponding feedback field.

For example, in this case, for a structure of the beamforming report,refer to Table 2.

An example is used for description with reference to Table 2. In thebeamforming report, a MIMO control field 1 is used to indicate aconfiguration parameter used for channel state information included in afeedback field 1. The channel state information included in the feedbackfield 1 is the channel state information of the feedback unitcorresponding to the first to the n^(th) bits in the processing modebitmap in step S101, and the channel state information included in thefeedback field 1 is processed in a processing mode indicated by a valueof the first to the n^(th) bits in the processing mode bitmap. A MIMOcontrol field 2 is used to indicate a configuration parameter used forchannel state information included in a feedback field 2. The channelstate information included in the feedback field 2 is the channel stateinformation of the feedback unit corresponding to the (n+1)^(th) to the(2n)^(th) bits in the processing mode bitmap in step S101, and thechannel state information included in the feedback field 2 is processedin a processing mode indicated by a value of the (n+1)^(th) to the(2n)^(th) bits in the processing mode bitmap.

TABLE 2 Sequence number Field 0 Category field 1 Action field 2 MIMOcontrol field 1 3 Feedback field 1 4 MIMO control field 2 5 Feedbackfield 2 . . . . . .

Optionally, when the beamforming report uses the structure shown inTable 2, for the MIMO control field, refer to a structure shown in FIG.4. As shown in FIG. 4, the MIMO control field includes: a number ofcolumns (Nc) index, a number of rows (Nr) index, a channel bandwidth, anumber of grouping (Ng), codebook information, a feedback type, aremaining feedback segment, a first feedback segment, a resource unitstart index (RU start index), a resource unit end index (RU end index),a sounding dialog token number, and one or more reserved bits.

Alternatively, when the beamforming report uses the structure shown inTable 2, for the MIMO control field, refer to a structure shown in FIG.5. As shown in FIG. 5, the MIMO control field further includesprocessing mode indication information. The processing mode indicationinformation is used to indicate a processing mode used for channel stateinformation included in a corresponding feedback field.

In another implementation, the beamforming report includes only one MIMOcontrol field, and the MIMO control field is used to indicateconfiguration parameters used for channel state information included inall feedback fields in the beamforming report.

For example, in this case, for a structure of the beamforming report,refer to Table 3.

An example is used for description with reference to Table 3. In thebeamforming report, the MIMO control field is used to indicateconfiguration parameters used for channel state information included ina feedback field 1, a feedback field 2, a feedback field 3, and anotherfeedback field (not shown in Table 3). The channel state informationincluded in the feedback field 1 is the channel state information of thefeedback unit corresponding to the first to the n^(th) bits in theprocessing mode bitmap in step S101, and the channel state informationincluded in the feedback field 1 is processed in a processing modeindicated by a value of the first to the n^(th) bits in the processingmode bitmap. The channel state information included in the feedbackfield 2 is the channel state information of the feedback unitcorresponding to the (n+1)^(th) to the (2n)^(th) bits in the processingmode bitmap in step S101, and the channel state information included inthe feedback field 2 is processed in a processing mode indicated by avalue of the (n+1)^(th) to the (2n)^(th) bits in the processing modebitmap. The channel state information included in the feedback field 3is channel state information of a feedback unit corresponding to the(2n+1)^(th) to the (3n)^(th) bits in the processing mode bitmap in stepS101, and the channel state information included in the feedback field 3is processed in a processing mode indicated by a value of the(2n+1)^(th) to the (3n)^(th) bits in the processing mode bitmap.

TABLE 3 Sequence number Field 0 Category field 1 Action field 2 MIMOcontrol field 3 Feedback field 1 4 Feedback field 2 5 Feedback field 3 .. . . . .

Optionally, when the beamforming report uses the structure shown inTable 3, for the MIMO control field, refer to a structure shown in FIG.4.

Alternatively, when the beamforming report uses the structure shown inTable 3, for the MIMO control field, refer to a structure shown in FIG.6. As shown in FIG. 6, the MIMO control field further includes aprocessing mode bitmap. The processing mode bitmap is used to indicate aprocessing mode used for channel state information included in eachfeedback field in the beamforming report.

Optionally, as shown in Table 4, the processing mode bitmap may also beused as an independent field in the beamforming report, and have anindependent sequence number. This is not limited in this embodiment ofthis application.

TABLE 4 Sequence number Field 0 Category field 1 Action field 2Processing mode bitmap 3 MIMO control field 4 Feedback field 1 5Feedback field 2 6 Feedback field 3 . . . . . .

Optionally, if the MIMO control field provided in this embodiment ofthis application is applied to the next generation 802.11 standard,compared with a MIMO control field in the 802.11ax standard, in the MIMOcontrol fields shown in FIG. 4 to FIG. 6, the channel bandwidth, theresource unit start index, and the resource unit end index occupy morebits, such that a higher bandwidth and more RUs can be indicated. In theMIMO control fields shown in FIG. 4 to FIG. 6, the number of columnsindex and the number of rows index occupy more bits, such that morespatial streams can be indicated.

In addition, it should be noted that in Table 2, Table 3, or Table 4,the category field is used to indicate a category to which the MAC framebelongs. The action field is used to indicate a subcategory to which theMAC frame belongs.

Based on the technical solution shown in FIG. 3, every n bits in theprocessing mode bitmap correspond to one feedback unit, and the value ofthe n bits is used to indicate the processing mode of the channel stateinformation of the corresponding feedback unit. It may be understoodthat different processing modes correspond to different feedbackoverheads and different feedback precision. Therefore, for channel stateinformation of some feedback units (for example, relatively importantchannels), the beamformer may indicate, using the processing modebitmap, the beamformee to use a processing mode with relatively highfeedback precision, to ensure feedback precision. For channel stateinformation of some other feedback units (for example, unimportantchannels), the beamformer may indicate, using the processing modebitmap, the beamformee to use a processing mode with relatively lowfeedback overheads, to reduce feedback overheads. In this way, thebeamformee may process channel state information of different feedbackunits in proper processing modes, to implement balance between feedbackoverheads and feedback precision of the channel state information whenthe channel state information is fed back.

The following describes the channel state information feedback method inFIG. 3 with reference to various application scenarios.

FIG. 7 shows a channel state information feedback method according tothis application. The method includes the following steps.

S201: A beamformer generates and sends an NDPA frame, where the NDPAframe includes a processing mode bitmap.

For example, FIG. 8 is a schematic structural diagram of an NDPA frameaccording to an embodiment of this application. As shown in FIG. 8,station information in the NDPA frame may include a processing modebitmap. The processing mode bitmap included in the station informationis applicable to only a beamformee corresponding to the stationinformation. It should be noted that in the NDPA frame, processing modebitmaps included in different station information may be the same, ormay be different.

For example, FIG. 9 is a schematic structural diagram of another NDPAframe according to an embodiment of this application. As shown in FIG.9, common info of the NDPA frame includes a processing mode bitmap. Theprocessing mode bitmap is applicable to a beamformee corresponding toeach piece of station information in the NDPA frame.

It should be noted that, in this embodiment of this application, fordetailed descriptions of the processing mode bitmap included in the NDPAframe, refer to step S101. Details are not described again in thisembodiment of this application.

With reference to FIG. 8 and FIG. 9, the NDPA frame includes: a MACheader, a sounding dialog token field, one or more pieces of stationinformation, and a frame check sequence (FCS) field.

The MAC header includes: (1) a frame control field, used to indicate atype of the MAC frame; (2) a duration field, used to indicate durationof occupying a channel by the MAC frame and a correspondingacknowledgment frame; (3) a receiving address (RA) field, used toidentify a receive end of the MAC frame; and (4) a transmitting address(TA) field, used to identify a transmit end of the MAC frame.

The station information may further include one or more of the followingparameters: an association identifier (AID), partial bandwidthinformation, a feedback type, an Ng, a disambiguation bit, a codebooksize, or a number of columns index. The partial bandwidth informationincludes a resource unit start index and a resource unit end index.

The frame check sequence field is used to enable the receive end todetect whether a received MAC frame is correct.

Optionally, as shown in FIG. 8, the sounding dialog token field in theNDPA frame includes an NDPA type and a sounding dialog token number. TheNDPA type is used to indicate a type of the NDPA frame, that is,indicate that the NDPA frame is a very high throughput (VHT) NDPA frame(that is, an NDPA frame in the 802.11ac standard), an HE NDPA frame, aranging NDPA frame, or an EHT NDPA frame. For example, the NDPA typeoccupies two bits. If a value of the two bits is 00, the NDPA typeindicates that the NDPA frame is the VHT NDPA frame. If a value of thetwo bits is 01, the NDPA type indicates that the NDPA frame is the HENDPA frame.

If a value of the two bits is 10, the NDPA type indicates that the NDPAframe is the ranging NDPA frame. If a value of the two bits is 11, theNDPA type indicates that the NDPA frame is the EHT NDPA frame. Thesounding dialog token number is used to identify a sounding dialog.

Optionally, as shown in FIG. 8, in the NDPA frame, if the stationinformation includes a special AID, that is, a value of an AID field inthe station information is a special value, for example, 2045, thestation information may be used for another function other than afunction of requesting the beamformee to feed back channel stateinformation. In this case, another field in the station information isused to indicate other information. Optionally, when the stationinformation is used for the other function, the station informationfurther includes an NDPA subtype, where the NDPA subtype is used toindicate a subtype to which the NDPA frame belongs.

S202: The beamformer sends an NDP.

S203 (optional): The beamformer sends a BRP trigger frame.

During implementation, in a single-user feedback procedure, thebeamformer does not perform step S203; and in a multi-user feedbackprocedure, the beamformer performs step S203.

S204 is the same as step S102. For detailed descriptions, refer to theembodiment shown in FIG. 3. Details are not described herein again.

FIG. 10 shows a channel state information feedback method according toan embodiment of this application. The method includes the followingsteps.

S301: A beamformer sends an NDPA frame.

S302: The beamformer sends an NDP.

S303: The beamformer generates and sends a BRP trigger frame, where theBRP trigger frame includes a processing mode bitmap.

Optionally, FIG. 11 is a schematic structural diagram of a BRP triggerframe according to an embodiment of this application. As shown in FIG.11, user information of the BRP trigger frame may include a processingmode bitmap. The processing mode bitmap included in the user informationis applicable to only a beamformee corresponding to the userinformation. It should be noted that in the BRP trigger frame,processing mode bitmaps included in different user information may bethe same, or may be different.

Optionally, FIG. 12 is a schematic structural diagram of a BRP triggerframe according to an embodiment of this application. As shown in FIG.12, common info of the BRP trigger frame includes a processing modebitmap. The processing mode bitmap is applicable to a beamformeecorresponding to each piece of user information in the BRP triggerframe.

It should be noted that, in this embodiment of this application, fordetailed descriptions of the processing mode bitmap included in the BRPtrigger frame, refer to step S101. Details are not described again inthis embodiment of this application.

With reference to FIG. 11 and FIG. 12, the BRP trigger frame includes: aMAC header, common info, a user info list, and an FCS field. The commoninfo includes some common information such as a trigger type and anuplink length. For content, refer to the 802.11 standard. Details arenot described herein. The user info list includes one or more pieces ofuser information. The user information includes one or more of thefollowing parameters: an AID, resource unit allocation (RU allocation),an uplink (UL) forward error correction (FEC) coding type, an ULmodulation and coding scheme (MCS), UL dual-carrier modulation (DCM),spatial stream allocation/random access resource unit information, anuplink target received signal strength indication, a feedback segmentretransmission bitmap, or one or more reserved bits. For meanings of theforegoing parameters, refer to the 802.11 standard. Details are notdescribed herein.

S304 is the same as step S104. For detailed descriptions, refer to theembodiment shown in FIG. 3. Details are not described herein again.

FIG. 13 shows a channel state information feedback method according toan embodiment of this application. The method includes the followingsteps.

S401: A beamformer generates and sends a MAC frame, where the MAC frameincludes at least two pieces of user information corresponding to atarget beamformee, and at least one type of configuration parameters inconfiguration parameters included in the at least two pieces of userinformation have different values.

The user information is used to indicate the corresponding beamformee tofeed back channel state information. For example, the configurationparameter included in the user information includes one or more of thefollowing: a resource unit start index, a resource unit end index,processing mode indication information, a number of grouping, orcodebook information. The processing mode indication information is usedto indicate a processing mode of the channel state information.

The resource unit start index and the resource unit end index are usedto indicate the beamformee to feed back channel state information of aresource unit at a specific part. Therefore, if the at least two piecesof user information include different resource unit start indexes and/ordifferent resource unit end indexes, the target beamformee separatelyfeeds back channel state information of resource units at differentparts based on the at least two pieces of user information.

The processing mode indication information, the number of grouping, andthe codebook information are used to indicate the processing mode of thechannel state information. Therefore, if the at least two pieces of userinformation include different processing mode indication information,different numbers of grouping, and/or different codebook information,the target beamformee uses different processing modes for the channelstate information corresponding to the at least two pieces of userinformation.

Optionally, the MAC frame is an NDPA frame or a BRP trigger frame. Itshould be noted that, in the NDPA frame, the user information includedin the MAC frame is usually referred to as station information.

In an optional implementation, the beamformer sends the MAC frame in abroadcast manner.

S402: The beamformer receives a beamforming report sent by the targetbeamformee, where the beamforming report includes the channel stateinformation respectively corresponding to the at least two pieces ofuser information.

Optionally, the beamforming report includes a plurality of feedbackfields, each feedback field corresponds to one piece of userinformation, and the feedback field includes channel state informationrequested by the corresponding user information.

In an implementation, the beamforming report includes a plurality ofMIMO control fields, each MIMO control field corresponds to one feedbackfield, and the MIMO control field is used to indicate a configurationparameter used for channel state information included in thecorresponding feedback field. For example, in this case, for a structureof the beamforming report, refer to Table 2, and for a structure of theMIMO control field, refer to FIG. 4 or FIG. 5.

In another implementation, the beamforming report includes only one MIMOcontrol field, and the MIMO control field is used to indicateconfiguration parameters used for channel state information included inall feedback fields in the beamforming report. For example, in thiscase, for a structure of the beamforming report, refer to Table 3, andfor the MIMO control field, refer to FIG. 4, FIG. 6, or FIG. 14.

As shown in FIG. 14, the MIMO control field includes: quantityindication information, a processing mode bitmap, a number of groupingbitmap, and a codebook information bitmap. The quantity indicationinformation is used to indicate a quantity of feedback fields includedin the beamforming report. The processing mode bitmap is used toindicate a processing mode used for channel state information includedin each feedback field in the beamforming report. The number of groupingbitmap is used to indicate a number of grouping used for the channelstate information included in each feedback field in the beamformingreport. The codebook information bitmap is used to indicate codebookinformation used for the channel state information included in eachfeedback field in the beamforming report.

In addition, as shown in FIG. 14, the MIMO control field may furtherinclude a plurality of pieces of partial bandwidth information, and thepartial bandwidth information includes a resource unit start index and aresource unit end index. Each piece of partial bandwidth informationcorresponds to one feedback field, and the partial bandwidth informationis used to indicate that channel state information included in thecorresponding feedback field is channel state information of a resourceunit at a specific part. Using FIG. 14 as an example, a resource unitstart index 1 and a resource unit end index 1 correspond to a feedbackfield 1, and by analogy, a resource unit start index n and a resourceunit end index n correspond to a feedback field n.

Based on the technical solution shown in FIG. 13, the MAC frame mayinclude the at least two pieces of user information corresponding to thetarget beamformee, and the at least one type of configuration parametersin the configuration parameters included in the at least two pieces ofuser information have different values. To be more specific, thebeamformer may indicate, using a plurality of pieces of user informationcorresponding to the target beamformee in the MAC frame, the targetbeamformee to feed back a plurality of pieces of channel stateinformation, where the plurality of pieces of channel state informationmay be processed in different processing modes, and/or the plurality ofpieces of channel state information are channel state information ofresource units at different parts. In this way, the channel stateinformation is flexibly fed back.

The following describes the technical solution in FIG. 13 with referenceto various application scenarios.

FIG. 15 shows a channel state information feedback method according toan embodiment of this application. The method includes the followingsteps.

S501: A beamformer generates and sends an NDPA frame, where the NDPAframe includes at least two pieces of station information correspondingto a target beamformee, and at least one type of configurationparameters in configuration parameters included in the at least twopieces of station information have different values.

In an implementation, the NDPA frame includes a plurality of pieces ofstation information, and at least two of the plurality of pieces ofstation information have a same AID. It may be understood that the atleast two pieces of station information having the same AID correspondto a same beamformee. For example, as shown in FIG. 16, AIDs of stationinformation 1 and station information 2 in the NDPA frame are both anAID 1. In addition, at least one type of configuration parameters inconfiguration parameters included in the station information 1 and thestation information 2 have different values. For example, in the stationinformation 1, a resource unit start index is 0, and a resource unit endindex is 8; and in the station information 2, a resource unit startindex is 18, and a resource unit end index is 26. In this way, thestation information 1 is used to request the beamformee to feed backchannel state information of the first to the ninth 26-subcarrier RUs.The station information 2 is used to request the beamformee to feed backchannel state information of the nineteenth to the twenty-seventh26-subcarrier RUs. In other words, the station information 1 and thestation information 2 are respectively used to request channel stateinformation of different RUs from the same beamformee. For anotherexample, an Ng indication included in the station information 1 is 4,and an Ng indication included in the station information 2 is 16. Inthis way, a number of grouping of the channel state informationrequested by the station information 1 is different from a number ofgrouping of the channel state information requested by the stationinformation 2.

Optionally, partial bandwidth information included in the stationinformation 1 is different from partial bandwidth information includedin the station information 2.

Optionally, in the NDPA frame, locations of a plurality of pieces ofstation information with a same AID are adjacent. In this way, in aprocessing of reading the NDPA frame, if the beamformee determines thatAIDs included in two pieces of adjacent station information aredifferent, and an AID included in the previous station information inthe two pieces of adjacent station information is the same as an AID ofthe beamformee, the beamformee does not need to continue to readsubsequent station information, thereby reducing duration in which thebeamformee reads information.

Further, in the NDPA frame, if the plurality of pieces of adjacentstation information have the same AID, an AID field is omitted instation information other than the first piece of station information inthe plurality of pieces of station information, to reduce transmissionoverheads. In addition, quantity indication information is added to thefirst piece of station information in the plurality of pieces of stationinformation, and the quantity indication information is used to indicatea quantity of pieces of station information with the same AID. Withreference to FIG. 17, if station information 2 and station information 3in an NDPA frame have a same AID, an AID field is removed from thestation information 3. In addition, quantity indication information isadded to the station information 2, and the quantity indicationinformation is used to indicate that a quantity of pieces of stationinformation with the same AID is 2.

S502: The beamformer sends an NDP.

S503 (optional): The beamformer sends a BRP trigger frame.

During implementation, in a single-user feedback procedure, thebeamformer does not perform step S503; and in a multi-user feedbackprocedure, the beamformer performs step S503.

S504 is the same as step S402. For detailed descriptions, refer to theembodiment shown in FIG. 13. Details are not described herein again.

FIG. 18 shows another channel state information feedback methodaccording to an embodiment of this application. The method includes thefollowing steps.

S601: A beamformer sends an NDPA frame.

S602: The beamformer sends an NDP.

S603: The beamformer generates and sends a BRP trigger frame, where theBRP trigger frame includes at least two pieces of user informationcorresponding to a target beamformee, and at least one type ofconfiguration parameters in configuration parameters included in the atleast two pieces of user information have different values.

Optionally, FIG. 19 is a schematic structural diagram of a BRP triggerframe according to an embodiment of this application. As shown in FIG.19, the BRP trigger frame further includes the following parameters: aresource unit start index, a resource unit end index, processing modeindication information, a number of grouping, and codebook information.

In an implementation, the BRP trigger frame includes a plurality ofpieces of user information, and at least two of the plurality of piecesof user information have a same AID. For example, as shown in FIG. 20,in the BRP trigger frame, AIDs in both user information 4 and userinformation 5 are an AID 1. In addition, at least one type ofconfiguration parameters in configuration parameters included in theuser information 4 and the user information 5 have different values. Forexample, it is assumed that, in the user information 4, a resource unitstart index is 6, a resource unit end index is 10, and an Ng indicationis 4; and in the user information 5, a resource unit start index is 20,a resource unit end index is 25, and an Ng indication is 8. In this way,the user information 4 is used to request a beamformee corresponding tothe AID 1 to feed back channel state information of the seventh to theeleventh 26-subcarrier RUs, and a number of grouping used for thechannel state information is 4. The user information 5 is used torequest the beamformee corresponding to the AID 1 to feed back channelstate information of the twenty-first to the twenty-sixth 26-subcarrierRUs, and a number of grouping used for the channel state information is8.

Optionally, in the BRP trigger frame, locations of a plurality of piecesof user information with a same AID are adjacent, to reduce duration inwhich the beamformee reads information.

Further, in the BRP trigger frame, if the plurality of pieces ofadjacent station information have the same AID, an AID field is omittedin station information other than the first piece of station informationin the plurality of pieces of station information, to reducetransmission overheads. In addition, quantity indication information isadded to the first piece of station information in the plurality ofpieces of station information, and the quantity indication informationis used to indicate a quantity of pieces of station information with thesame AID. With reference to FIG. 21, if user information 4, userinformation 5, and user information 6 in the BRP trigger frame have asame AID, an AID field is removed from each of the user information 5and the user information 6. In addition, quantity indication informationis added to the user information 4, and the quantity indicationinformation is used to indicate that a quantity of pieces of stationinformation with the same AID is 3.

S604 is the same as step S402. For detailed descriptions, refer to theembodiment shown in FIG. 13. Details are not described herein again.

The foregoing mainly describes the solutions provided in the embodimentsof this application from a perspective of interaction between networkelements. It may be understood that, to implement the foregoingfunctions, each network element, for example, the beamformer and thebeamformee, includes corresponding hardware structures and/or softwaremodules for performing the functions. A person skilled in the art shouldeasily be aware that, in combination with units and algorithm steps ofthe examples described in the embodiments disclosed in thisspecification, this application may be implemented in a hardware form orin a form of combining hardware with computer software. Whether afunction is performed by hardware or hardware driven by computersoftware depends on particular applications and design constraints ofthe technical solutions. A person skilled in the art may use differentmethods to implement the described functions for each particularapplication, but it should not be considered that the implementationgoes beyond the scope of this application.

In the embodiments of this application, the apparatus may be dividedinto function modules based on the foregoing method examples. Forexample, each function module may be obtained through division based oneach corresponding function, or two or more functions may be integratedinto one processing module. The integrated module may be implemented ina form of hardware, or may be implemented in a form of a softwarefunction module. It should be noted that, in the embodiments of thisapplication, division into modules is an example, and is merely logicalfunction division. During actual implementation, another division mannermay be used. An example in which each function module is obtainedthrough division based on each corresponding function is used below fordescription.

FIG. 22 is a schematic structural diagram of a communications apparatusaccording to an embodiment of this application. As shown in FIG. 22, thecommunications apparatus includes a receiving module 101, a sendingmodule 102, and a processing module 103.

In an implementation, if the communications apparatus is used as abeamformer, the processing module 103 is configured to generate a MACframe. The MAC frame includes a processing mode bitmap, every n bits inthe processing mode bitmap correspond to one feedback unit, a value ofthe n bits is used to indicate a processing mode of channel stateinformation of the corresponding feedback unit, and n is a positiveinteger. The sending module 102 is configured to send the MAC framegenerated by the processing module 103. The receiving module 101 isconfigured to receive a beamforming report sent by a beamformee. Thebeamforming report includes one or more feedback fields, each feedbackfield corresponds to one feedback unit, the feedback field includeschannel state information of the corresponding feedback unit, and thechannel state information included in the feedback field is processed ina processing mode indicated by the processing mode bitmap.

Optionally, the feedback unit is a segment, a resource unit, or achannel.

Optionally, the MAC frame is an NDPA frame or a beamforming report polltrigger frame.

In an implementation, if the communications apparatus is used as abeamformee, the receiving module 101 is configured to receive a MACframe. The MAC frame includes a processing mode bitmap, every n bits inthe processing mode bitmap correspond to one feedback unit, a value ofthe n bits is used to indicate a processing mode of channel stateinformation of the corresponding feedback unit, and n is a positiveinteger. The processing module 103 is configured to generate abeamforming report. The beamforming report includes one or more feedbackfields, each feedback field corresponds to one feedback unit, thefeedback field includes channel state information of the correspondingfeedback unit, and the channel state information included in thefeedback field is processed in a processing mode indicated by theprocessing mode bitmap. The sending module 102 is configured to send thebeamforming report to a beamformer.

Optionally, the feedback unit is a segment, a resource unit, or achannel.

Optionally, the MAC frame is an NDPA frame or a beamforming report polltrigger frame.

In another implementation, if the communications apparatus is used as abeamformer, the processing module 103 is configured to generate a MACframe. The MAC frame includes at least two pieces of user informationcorresponding to a target beamformee, and at least one type ofconfiguration parameters in configuration parameters included in the atleast two pieces of user information have different values. The sendingmodule 102 is configured to send the MAC frame generated by theprocessing module 103. The receiving module 101 is configured to receivea beamforming report sent by the target beamformee. The beamformingreport includes channel state information respectively corresponding tothe at least two pieces of user information.

Optionally, the user information includes one or more of the followingconfiguration parameters: a resource unit start index, a resource unitend index, processing mode indication information, a number of grouping,or codebook information.

Optionally, the MAC frame is an NDPA frame or a beamforming report polltrigger frame.

In another implementation, if the communications apparatus is used as atarget beamformee, the receiving module 101 is configured to receive aMAC frame. The MAC frame includes at least two pieces of userinformation corresponding to the target beamformee, and at least onetype of configuration parameters in configuration parameters included inthe at least two pieces of user information have different values. Theprocessing module 103 is configured to generate a beamforming report.The beamforming report includes channel state information respectivelycorresponding to the at least two pieces of user information. Thesending module 102 is configured to send the beamforming report to abeamformer.

With reference to FIG. 3, FIG. 7, FIG. 10, FIG. 13, FIG. 15, and FIG.18, if the communications apparatus is used as a beamformer, thereceiving module 101 is configured to perform step S102 in FIG. 3, stepS204 in FIG. 7, step S304 in FIG. 10, step S402 in FIG. 13, step S504 inFIG. 15, step S604 in FIG. 18, and/or another process used for thetechnical solutions described in this specification. The sending module102 is configured to perform step S101 in FIG. 3, steps S201 to S203 inFIG. 7, steps S301 to S303 in FIG. 10, step S401 in FIG. 13, steps S501to S503 in FIG. 15, steps S601 to S603 in FIG. 18, and/or anotherprocess used for the technical solutions described in thisspecification.

If the communications apparatus is used as a beamformee, the receivingmodule 101 is configured to perform step S101 in FIG. 3, steps S201 toS203 in FIG. 7, steps S301 to S303 in FIG. 10, step S401 in FIG. 13,steps S501 to S503 in FIG. 15, steps S601 to S603 in FIG. 18, and/oranother process used for the technical solutions described in thisspecification. The sending module 102 is configured to perform step S102in FIG. 3, step S204 in FIG. 7, step S304 in FIG. 10, step S402 in FIG.13, step S504 in FIG. 15, step S604 in FIG. 18, and/or another processused for the technical solutions described in this specification. Allrelated content of the steps in the foregoing method embodiments may becited in function descriptions of the corresponding function modules.Details are not described herein again.

The communications apparatus provided in the embodiments of thisapplication may be implemented in a plurality of product forms. Forexample, the communications apparatus may be configured as ageneral-purpose processing system. For another example, thecommunications apparatus may be implemented using a general busarchitecture. For another example, the communications apparatus may beimplemented by an application-specific integrated circuit (ASIC). Thefollowing provides several possible product forms of the communicationsapparatus in the embodiments of this application. It should beunderstood that the following product forms are merely examples, and donot limit the possible product forms of the communications apparatus inthe embodiments of this application.

FIG. 23 is a structural diagram of a possible product form of acommunications apparatus according to an embodiment of this application.

In a possible product form, the communications apparatus in thisembodiment of this application may be a communications device, and thecommunications device includes a processor 201 and a transceiver 202.Optionally, the communications device further includes a storage medium203. The processor 201 is configured to perform the channel stateinformation feedback methods shown in FIG. 3, FIG. 7, FIG. 10, FIG. 13,FIG. 15, and FIG. 18. The transceiver 202 is controlled by the processor201, and is configured to perform the channel state information feedbackmethods shown in FIG. 3, FIG. 7, FIG. 10, FIG. 13, FIG. 15, and FIG. 18.

In another possible product form, the communications apparatus in thisembodiment of this application may be alternatively implemented by ageneral-purpose processor, that is, implemented by a commonly knownchip. The general-purpose processor includes a processing circuit 201and a transceiver pin 202. Optionally, the general-purpose processor mayfurther include a storage medium 203. The processing circuit 201 isconfigured to perform the channel state information feedback methodsshown in FIG. 3, FIG. 7, FIG. 10, FIG. 13, FIG. 15, and FIG. 18. Thetransceiver pin 202 is controlled by the processing circuit 201, and isconfigured to perform the channel state information feedback methodsshown in FIG. 3, FIG. 7, FIG. 10, FIG. 13, FIG. 15, and FIG. 18.

In another possible product form, the communications apparatus in thisembodiment of this application may be alternatively implemented usingthe following circuits or components: one or more field programmablegate arrays (FPGA), a programmable logic device (PLD), a controller, astate machine, gate logic, a discrete hardware component, any othersuitable circuit, or any combination of circuits that can performvarious functions described in this application.

Although this application is described with reference to theembodiments, in a process of implementing this application that claimsprotection, a person skilled in the art may understand and implementanother variation of the disclosed embodiments by viewing theaccompanying drawings, disclosed content, and the appended claims. Inthe claims, “comprising” does not exclude another component or anotherstep, and “a” or “one” does not exclude a case of plurality. A singleprocessor or another unit may implement several functions enumerated inthe claims.

Some measures are recorded in dependent claims that are different fromeach other, but this does not mean that these measures cannot becombined to produce a better effect.

Although this application is described with reference to examplefeatures and the embodiments thereof, it is clear that variousmodifications and combinations may be made to this application withoutdeparting from the spirit and scope of this application.Correspondingly, the specification and accompanying drawings are merelyexample descriptions of this application defined by the appended claims,and are considered as any of or all modifications, variations,combinations, or equivalents that cover the scope of this application.It is clear that, a person skilled in the art can make variousmodifications and variations to this application without departing fromthe spirit and scope of this application. This application is intendedto cover these modifications and variations of this application providedthat they fall within the scope of the claims of this application andtheir equivalent technologies.

What is claimed is:
 1. A channel state information feedback method,wherein the method comprises: sending, by a beamformer, a media accesscontrol (MAC) frame comprising a processing mode bitmap, wherein nconsecutive bits in the processing mode bitmap correspond to a feedbackunit, wherein a value of the n consecutive bits indicates a processingmode, and wherein n is a positive integer; and receiving, by thebeamformer, a beamforming report from a beamformee, wherein thebeamforming report comprises a feedback field corresponding to thefeedback unit, wherein the feedback field comprises channel stateinformation of the corresponding feedback unit, and wherein the channelstate information is processed in the processing mode indicated by theprocessing mode bitmap.
 2. The channel state information feedback methodaccording to claim 1, wherein the feedback unit is a segment.
 3. Thechannel state information feedback method according to claim 1, whereinthe feedback unit is a resource unit.
 4. The channel state informationfeedback method according to claim 1, wherein the feedback unit is achannel.
 5. The channel state information feedback method according toclaim 1, wherein the MAC frame is a null data packet announcement (NDPA)frame.
 6. The channel state information feedback method according toclaim 1, wherein the MAC frame is a beamforming report poll triggerframe.
 7. A channel state information feedback method, wherein themethod comprises: receiving, by a beamformee, a media access control(MAC) frame from a beamformer, wherein the MAC frame comprises aprocessing mode bitmap, wherein n consecutive bits in the processingmode bitmap correspond to a feedback unit, wherein a value of the n bitsindicates a processing mode, and wherein n is a positive integer; andsending, by the beamformee, a beamforming report to the beamformer,wherein the beamforming report comprises a feedback field correspondingto the feedback unit, wherein the feedback field comprises channel stateinformation of the corresponding feedback unit, and wherein the secondchannel state information is processed in the processing mode indicatedby the processing mode bitmap.
 8. The channel state information feedbackmethod according to claim 7, wherein the feedback unit is a segment. 9.The channel state information feedback method according to claim 7,wherein the feedback unit is a resource unit.
 10. The channel stateinformation feedback method according to claim 7, wherein the feedbackunit is a channel.
 11. The channel state information feedback methodaccording to claim 7, wherein the MAC frame is a null data packetannouncement (NDPA) frame.
 12. The channel state information feedbackmethod according to claim 7, wherein the MAC frame is a beamformingreport poll trigger frame.
 13. A communications apparatus, comprising: atransmitter configured to send a media access control (MAC) frame,wherein the MAC frame comprises a processing mode bitmap, wherein nconsecutive bits in the processing mode bitmap correspond to a feedbackunit, wherein a value of the n bits indicates a processing mode, andwherein n is a positive integer; and a receiver configured to receive abeamforming report from a beamformee, wherein the beamforming reportcomprises a feedback field corresponding to the feedback unit, whereinthe feedback field comprises channel state information of thecorresponding feedback unit, and wherein the channel state informationis processed in the processing mode indicated by the processing modebitmap.
 14. The communications apparatus according to claim 13, whereinthe feedback unit is a segment.
 15. The communications apparatusaccording to claim 13, wherein the feedback unit is a resource unit. 16.The communications apparatus according to claim 13, wherein the feedbackunit is a channel.
 17. The communications apparatus according to claim13, wherein the MAC frame is a null data packet announcement (NDPA)frame or a beamforming report poll trigger frame.
 18. A communicationsapparatus, comprising: a receiver configured to receive a media accesscontrol (MAC) frame from a beamformer, wherein the MAC frame comprises aprocessing mode bitmap, wherein n consecutive bits in the processingmode bitmap correspond to a feedback unit, wherein a value of the n bitsindicates a processing mode, and wherein n is a positive integer; and atransmitter configured to send a beamforming report to the beamformer,wherein the beamforming report comprises a feedback field correspondingto the feedback unit, wherein the feedback field comprises channel stateinformation of the corresponding feedback unit, and wherein the channelstate information is processed in a the processing mode indicated by theprocessing mode bitmap.
 19. The communications apparatus according toclaim 18, wherein the feedback unit is a segment, a resource unit, or achannel.
 20. The communications apparatus according to claim 18, whereinthe MAC frame is a null data packet announcement (NDPA) frame or abeamforming report poll trigger frame.